SAX parser exception, not well-formed

Estoy haciendo algo parecido en un treeview pero usando: field name=“search_value”. Estoy filtrando registros por rango de fechas basados en un campo timestamp: appointment_date.
Usando la siguiente linea en el xml:
<field name="search_value" eval="[('appointment_date', '>=', DateTime(hour=13, minute=0, second=0, microsecond=0, delta_days=0))]" pyson="1"/>

La vista funciona y me filtra las lineas cuya fecha es de hoy y superiores o futuras. Pero lo que busco es ver solo las del dia y probé con esto:
<field name="search_value" eval="[('appointment_date', '>=', DateTime(hour=13, minute=0, second=0, microsecond=0, delta_days=0)) , ('appointment_date', '<=', DateTime(hour=23, minute=30, second=0, microsecond=0, delta_days=0))]" pyson="1"/>
Le agrego un criterio de búsqueda y lo convierto en rango de fechas desde:hasta y me sale un error de xml mal formado.
El taceback:
10837 139805955221248 [2019-06-10 13:49:39,579] ERROR trytond.convert Error while parsing xml file:
In tag record: model ir.action.act_window with id action_gnuhealth_appointment_view.
Traceback (most recent call last):
File “/usr/lib/python3.5/xml/sax/expatreader.py”, line 210, in feed
self._parser.Parse(data, isFinal)
xml.parsers.expat.ExpatError: not well-formed (invalid token): line 1295, column 168

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “/home/nando/.virtualenvs/izasalepos/lib/python3.5/site-packages/trytond/convert.py”, line 447, in parse_xmlstream
self.sax_parser.parse(source)
File “/usr/lib/python3.5/xml/sax/expatreader.py”, line 110, in parse
xmlreader.IncrementalParser.parse(self, source)
File “/usr/lib/python3.5/xml/sax/xmlreader.py”, line 125, in parse
self.feed(buffer)
File “/usr/lib/python3.5/xml/sax/expatreader.py”, line 214, in feed
self._err_handler.fatalError(exc)
File “/usr/lib/python3.5/xml/sax/handler.py”, line 38, in fatalError
raise exception
xml.sax._exceptions.SAXParseException: :1295:168: not well-formed (invalid token)
Traceback (most recent call last):
File “/usr/lib/python3.5/xml/sax/expatreader.py”, line 210, in feed
self._parser.Parse(data, isFinal)
xml.parsers.expat.ExpatError: not well-formed (invalid token): line 1295, column 168

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “/home/nando/.virtualenvs/izasalepos/bin/trytond-admin”, line 21, in
admin.run(options)
File “/home/nando/.virtualenvs/izasalepos/lib/python3.5/site-packages/trytond/admin.py”, line 53, in run
pool.init(update=options.update, lang=list(lang))
File “/home/nando/.virtualenvs/izasalepos/lib/python3.5/site-packages/trytond/pool.py”, line 153, in init
lang=lang)
File “/home/nando/.virtualenvs/izasalepos/lib/python3.5/site-packages/trytond/modules/init.py”, line 453, in load_modules
_load_modules()
File “/home/nando/.virtualenvs/izasalepos/lib/python3.5/site-packages/trytond/modules/init.py”, line 422, in _load_modules
load_module_graph(graph, pool, update, lang)
File “/home/nando/.virtualenvs/izasalepos/lib/python3.5/site-packages/trytond/modules/init.py”, line 259, in load_module_graph
tryton_parser.parse_xmlstream(fp)
File “/home/nando/.virtualenvs/izasalepos/lib/python3.5/site-packages/trytond/convert.py”, line 447, in parse_xmlstream
self.sax_parser.parse(source)
File “/usr/lib/python3.5/xml/sax/expatreader.py”, line 110, in parse
xmlreader.IncrementalParser.parse(self, source)
File “/usr/lib/python3.5/xml/sax/xmlreader.py”, line 125, in parse
self.feed(buffer)
File “/usr/lib/python3.5/xml/sax/expatreader.py”, line 214, in feed
self._err_handler.fatalError(exc)
File “/usr/lib/python3.5/xml/sax/handler.py”, line 38, in fatalError
raise exception
xml.sax._exceptions.SAXParseException: :1295:168: not well-formed (invalid token)

Estoy usando Tryton 4.2, agradecería si me dan sus apreciaciones al respecto.

Saludos
Fernando

You can not use plain >, < nor & in XML file. You must encode them like &gt;, &lt and &amp;: see http://xml.silmaril.ie/specials.html